Quinolizinium anion exchange resins and monomers and methods for making them

ABSTRACT

Quinolizinium resins may be produced by quaternizing substituted vinyl pyridine polymers followed by subjecting the resulting product to a condensation reaction to obtain quinolizinium functionality. The resins are useful as ion exchange resins, adsorbents and catalysts.

This application is a division of my U.S. Pat. application Ser. No.550,493 filed Feb. 18, 1975, now U.S. Pat. No. 4,046,766, granted Sept.6, 1977.

This invention relates to quinolizinium condensation products ofquaternized vinyl pyridine polymers. More particularly the inventionconcerns methods of preparation and application of such quinoliziniumproducts as thermally stable resins in catalytic reaction, as additivesin the polymer industry or as adsorbents in the pollution field.

Certain quinolizinium type compounds have been described in the priorart, particularly those useful in the pharmaceutical applications. Forexample, British patent No. 916,507 describes a condensation process forthe production of dehydroquinolizinium compounds. Functionalizedquinolizinium monomer and polymers however appear not to have beenpreviously considered. The present invention deals with suchfunctionalized quinolizinium resins, modes of preparation andapplication.

According to the present invention, useful resins may be prepared byquaternizing substituted vinyl pyridine polymers and condensing theresulting product to quinolizinium resins. The resulting polymers havesurprisingly high thermal stability and additionally have beendiscovered to possess excellent physical stability, good regenerationefficiency -- particularly for the strong base resins, and increasedtotal anion exchange capacity. The resins have the further advantage inthat they are prepared by a method considered safer than the usualchloromethylation technique.

The resins of the invention may be macroreticular in nature whichmacroreticularity is achieved by well known processes as disclosed inBritish patents Nos. 932,125 and 932,126; and U.S. Pat. Nos. 3,275,548and 3,357,158. Alternatively, the resins may be gelular in nature.

Although the quinolizinium resins of the invention may have thestructure involving many aromatic rings, a preferred structure andgeneral synthesis is illustrated by the following reaction. ##STR1##WHERE R₁ is any activating group and may be alkoxy carbonyl or cyano;WHERE R₂ and R₃ are hydrogen, lower alkyl, phenyl, substituted loweralkyl, alkoxy or cyano groups

where R₁, R₂ and R₃ may be the same or different

where x is hydroxyl or halogen

More preferred values for R₁ are cyano and carboxyl.

More preferred values for R₂ are lower alkyl and hydrogen.

Vinyl pyridine polymers which may be used as starting compounds may beprepared by a variety of well known polymerization techniques, althoughsuspension polymerization is preferred.

The quaternization reaction of the polymer to the intermediatefunctionalized vinyl pyridine is also well known in the art. A preferredreactant for the applicant's resins is ethyl bromoacetate.

Quaternizing reaction conditions usually include temperatures of fromabout room temperature to reflux temperature under normal atmosphericpressure.

It is advantageous to use as starting compounds vinyl pyridine polymerswhich have utilized a comonomer such as divinyl pyridine or trimethylolpropane trimethacrylate during polymerization. Such comonomers, oftencalled crosslinkers, aid in achieving a strong bead formation. Anyutility which requires beads possessing strong physical stability shouldpreferably contain an adequate percentage of crosslinker. Utilitieswhich do not require such strong physical stability may utilize resinswhich are only lightly or not at all crosslinked. For example,applications requiring the ion exchange resin or catalyst in powderedform may use lightly crosslinked beads. The condensing reaction takesplace in the presence of a α-dicarbonyl compound preferably glyoxal ordiacetyl.

The condensation reaction conditions may vary widely although preferredconditions generally include reaction temperatures of 70 - 110° C.,preferably 75 - 90° C. This temperature is of course dependent on thepressures present during the reaction. Preferably however the reactionis carried out at atmospheric pressures, although super atmosphericpressures up to about 2 or 3 atmospheres might prove to be advantageousin lowering reaction times. The reagents during either quaternization orfollowing condensation reaction should be present in an amount of atleast one equivalent. Condensation reactions are more preferably run attemperatures of around 78° C.

Another preferred method of preparation involves the intermediateformation of a functionalized quinolizinium monomer. The startingcompound preferably is vinyl pyridine which is quaternized by a standardreactant to provide a product which may by a condensation reaction causethe formation of the functionalized monomer which subsequently may bepolymerized to the resin.

A specific reaction scheme illustrating this method is shown below##STR2## It should be understood that an analogous latitude applies asto the range of amounts and nature of reactants and reaction conditionswhich pertain to the synthesis illustrated by Reaction I. Similarly, thesubstituent groups may also vary. The above reactions I and IIillustrate that the resins of the inventor may be obtained by startingwith a polymeric vinyl pyridine or by a formed functionalizedquinolizinium monomer. It will be noted that in Formula 5 the vinylgroup, --CH═CH₂, is bonded directly to a quinolizinium ring carbon atom.

Specific resins prepared according to the process of the invention areshown in Table I.

                                      Table I                                     __________________________________________________________________________    Intermediate                                                                  Substituents                                                                           Quinolizinium Resin                                                  of Reaction I                    AEC   TSB                                    R.sub.1                                                                            R.sub.2                                                                           Name             R.sub.2                                                                           R.sub.3                                                                          meq/g dry                                                                           meq/g dry                              __________________________________________________________________________    CO.sub.2 CH.sub.3                                                                  H   Poly-2,3-dimethyl-7-vinyl quino-                                              lizinium Ion     H   CH.sub.3                                                                         3.95  1.91                                   CO.sub.2 CH.sub.3                                                                  H   Poly-3-vinylquinolizinium Ion                                                                  H   H  4.96  0.93                                   CO.sub.2 CH.sub.3                                                                  C.sub.6 H.sub.5                                                                   Poly-2,3-dimethyl-4-phenyl-7-                                                 vinylquinolizinium Ion                                                                         C.sub.6 H.sub.5                                                                   CH.sub.3                                                                         2.93  1.08                                   CO.sub.2 CH.sub.3                                                                  CH.sub.3                                                                          Poly-2,3,4-trimethyl-7-vinyl-                                                 quinolizinium Ion                                                                              CH.sub.3                                                                          CH.sub.3                                                                         3.70  1.76                                   H    CN  Poly-2,3-dimethyl-4-cyano-7-                                                  vinylquinolizinium Ion                                                                         CN  CH.sub.3                                                                         3.51  1.70                                   CO.sub.2 CH.sub.3                                                                  C.sub.6 H.sub.5                                                                   Poly-4-phenyl-7-vinyl-quinoli-                                                zinium Ion       C.sub.6 H.sub.5                                                                   H  3.53  0.50                                   CO.sub.2 CH.sub.3                                                                  CH.sub.3                                                                          Poly-4-methyl-7-vinyl-quino-                                                  lizinium Ion     CH.sub.3                                                                          H  4.63  0.79                                   H    CN  Poly-4-cyano-7-vinylquino-                                                    lizinium Ion     CN  H  4.38  0.70                                   __________________________________________________________________________

As mentioned hereinbefore, the resins of the invention have been testedfor thermal stability and physical stability. Resin A as describedhereinafter was tested against a commercial resin identified asAmberlite IRA-400 available from the Rohm and Haas Company for strongbase capacity at 140° C. The comparative thermal stability is determinedby the following test.

The resin as received is converted completely to the hydroxide formusing approximately 1000 mls. of 1 N NaOH for 15 mls. of resin. Theresin is rinsed with D. I. water and placed in an appropriate containercontaining excess D. I. water (at least a 20 to 1 water to resin ratio)and the container is placed in an oven of appropriate temperature (140°C.). Periodically, the sample is removed, completely converted to theHCl form and evaluated for solids content, and true strong basecapacity. After this, the resin is reconverted to the hydroxide formusing 1 N-HCl followed by 1 N-NaOH and replaced in the same temperatureenvironment. Several checks may be made at all temperatures to confirmthat the resins are completely in the hydroxide form during the testingperiods. The results indicate that the quinolizinium resins haveconsistently greater thermal stability than the comparative resins. Forexamle, quinolizinium ion Resin A retained essentially all its truestrong base capacity after 6.5 days at 140° C. vs. almost totaldestruction of the control resin Amberlite IRA-400 (93% loss of truestrong base capacity and 50% loss of volume). The results are shown inthe following table

    ______________________________________                                                            ABC       TSB                                                          Solids (meq/g)   (meq/g)                                         ______________________________________                                        Resin A        37.20    3.95      1.91                                        Resin A (140°,6.5 days)                                                               40.11    3.89      1.77                                        IRA-400        52.14    4.09      4.09                                        IRA-400 (140°,6.5 days)                                                               68.95    2.20      0.28                                        ______________________________________                                    

Physical stability is measured as a Chatillon value. The Chatillon testmeasures the force required to fracture a resin bead when placed betweentwo parallel plates, and receives its name from the apparatus used todetermine this friability or fragmentation force. Its purpose is tosimulate the frictional and pressure forces exerted on individual resinbeads in actual use.

These specifications generally include testing at least sixty, watersaturated, 20-30 mesh, resin beads. The average force required tofracture individual beads of anion resin in the hydroxide form or cationresin in the hydrogen form given as a number of grams per bead is termedthe Chatillon Value.

The resins of the invention when compared to commercial resins for theirphysical stability show results as indicated in the following Table II.

                  Table II                                                        ______________________________________                                        Resin                Chatillon Value                                          ______________________________________                                        Resin A, Macroreticular                                                                            1,098 g/bead                                             IRA-900, Macroreticular                                                                             300 g/bead                                              IRA-400, Gelular      50 g/bead                                               Resin A, Gelular      355 g/bead                                              ______________________________________                                    

As indicated hereinbefore, the resins are useful in a variety ofapplications. These applications utilizing the ion exchangecharacteristics, the adsorption characteristics and thermal stabilityinclude hot condensate flushing, purification processes of primarycoolant loops in nuclear reactant systems and waste stream purificationswhether such streams are aqueous or gaseous in nature.

The following examples serve to illustrate the invention further.

EXAMPLE I A. Preparation of Poly-2-methyl-5-vinylpyridine-7%Divinylbenzene (Reaction I)

    ______________________________________                                        Charges (3 mole scale)                                                        Aqueous Phase    Organic Phase                                                ______________________________________                                        960 g Water      51 g Divinylbenzene (80%)                                    390 g Sodium Chloride                                                                          525 g 2-Methyl-5-vinylpyridine                               45 g Primafloc C-3                                                                             309 g Diisobutyl Ketone                                      6 g Primafloc C-7                                                                              5.7 g Azo-bis-isobutyronitrile                               0.3 g Sodium Nitrite                                                          ______________________________________                                    

The aqueous phase is added to a 3-liter flask fitted with aconstant-torque stirrer, condenser, thermometer, and a nitrogeninlet-outlet system. The stirring rate is adjusted to 148 rpm. Afteradding the organic phase, the depth of the four-prong stirrer isadjusted to obtain the ideal suspension. The system is flushed withnitrogen and a constant sweep of nitrogen is maintained throughout thereaction period. The mixture is heated to 65° C. and maintained at thistemperature for 20 hours. Triton CR-32 (15 drops), a foam inhibitor, isadded to minimize foaming and the solution is heated to reflux. Thesolvents are azeotroped until no visible organic solvent distills. Theresin is filtered, washed with water, and dried in a vacuum at 50° C.overnight. The resulting weak base resin has the following properties:

    ______________________________________                                        Anion Exchange Capacity (meq/g)                                                                           7.11                                              Solids (%)                 40.80                                              Surface Area (m.sup.2 /g)  32.76                                              Porosity (cc/cc)            0.32                                              ______________________________________                                    

B. Preparation of Poly-2-methyl-5-vinylpyridine-N-carboethoxy Bromide(Reaction I)

Charges

30.0 g (0.18 equiv.) Macroreticular poly-2-methyl-5-vinylpyridine ofExample I (A) (7% divinylbenzene)

32.0 g (0.19 mole) Ethyl Bromoacetate

230 ml Methanol

The dried poly-2-methyl-5-vinylpyridine and 200 ml of the methanol areplaced in a 1-liter flask equipped with a stirrer, thermometer, andcondenser. The beads are allowed to swell for 30 minutes at 65° C. withagitation. After the swelling period the excess methanol is removed byfiltration. The ethyl bromoacetate dissolved in 20 ml of the methanol isadded to the swollen beads at room temperature (ca. 25° C.). Additionalmethanol (10 ml) is used to wash the last trace of reagent into thereaction flask. The reaction mixture is stirred at room temperature for30 minutes, reflux temperature (60-65° C.) for 4 hours, and for anadditional 15- 16 hours at room temperature. The resin is filtered,washed twice with methanol, and column washed with two bed volumes ofmethanol. Drying the resin in a vacuum oven at 50° C. for 2 hours gives61.9 g of yellow beads.

C. Preparation of the Quinolizinium Ion Resin - Resin A

Charges

31.0 g (0.09 equiv) Poly-2-methyl-5-vinylpyridine-N-carboethoxy Bromideof Example I (B)

9.0 g (0.105 mole) 2,3-Butanedione

13.0 g (0.101 mole) Di-n-butylamine

230 ml 2B (ethanol) Alcohol

The dried poly-2-methyl-5-vinylpyridine-N-carboethoxy bromide and 200 mlof the 2B alcohol are added to a flask equipped with a stirrer,thermometer, condenser, and gas inlet and outlet tubes. The apparatus isswept with nitrogen and a slow sweep of this gas is maintained duringthe reaction period. The beads are allowed to swell at refluxtemperature (78° C.) for 30 minutes with stirring. The excess solvent isremoved by filtration. At room temperature, the 2,3-butanedione anddi-n-butylamine are added followed by 30 ml of 2B alcohol. The reactionmixture is heated to reflux (78° C.) and maintained at this temperaturefor 4 hours. The black beads are filtered while warm (50° C.) and washedwith 3 × 80 ml portions of warm (50° C.). 2B alcohol, then transferredto a column and washed with methanol (1 pint). Drying the resin in avacuum oven at 50° C. for two hours gives 30.4 g of product in thebromide form. The resulting Resin A has the following properties:

    ______________________________________                                        Total Anion Exchange Capacity (meq/g)                                                                   3.95                                                True Strong Base Capacity (meq/g)                                                                       1.91                                                Solids %                  37.20                                               Apparent Density (g/cc)   0.855                                               True Density (g/cc)       1.095                                               Surface Area (m.sup.2 /g) 85.0                                                Porosity (cc/cc)          0.309                                               ______________________________________                                    

EXAMPLE II

Charges

10.0 g (0.035 equiv) Poly-2-methyl-5-vinylpyridine-N-carboethoxy bromideof Example I (B)

5.5 g (0.038 mole) 40% aqueous glyoxal

7.8 g (0.076 mole) sodium bisulfite

9.6 g (0.11 mole) sodium bicarbonate

Using the apparatus and nitrogen system described in Example 1, theintermediate 2 and 100 ml of deionized water are heated at 90° C. for 1hour. The excess water is removed by filtration and the resin is cooledto 40-50° C. The sodium bicarbonate dissolved in 30 ml of deionizedwater was added to the swollen beads while maintaining the temperatureat 40-50° C. A warm (60° C.) solution of the glyoxal and the sodiumbisulfite in 50 ml of deionized water is added. The temperature isincreased to 80° C. and maintained at this temperature for ten hours.Following the reaction period, the resin is filtered while warm (80°C.), washed with three bed volumes of methanol. Drying the resins at 50°C. in a vacuum oven for two hours gives 6.7 g of dark amber beads. Theresulting Resin B, characterized in that the R substituent as referredto in Resin I is hydrogen, has the following properties:

    ______________________________________                                        Total Anion Exchange Capacity (meq/g)                                                                   4.96                                                True Strong Base Capacity (meq/g)                                                                       0.93                                                Solids (%)                30.00                                               ______________________________________                                    

EXAMPLE III 1. Preparation of 2,3-Dimethyl-7-vinylquinolizinium bromidefollowing Reaction II

Charges

Reaction A

17.8 g (0.15 mole) 2-methyl-5-vinylpyridine

25.0 g (0.15 mole) Ethyl Bromoacetate

0.5 g Benzoquinone

150 ml Ethanol

Reaction B

12.9 g (0.15 mole) 2,3-Butanedione (Diacetyl)

19.7 g (0.15 mole) Di-n-butylamine

Reactions A and B are carried out in the same flask without theisolation of the intermediate.

The 2-methyl-5-vinylpyridine, benzoquinone, and ethanol are charged to a500 ml flask equipped with a stirrer, thermometer, and condenser. Theethyl bromoacetate is added and the dark solution is stirred at roomtemperature for 16 hours. The 2,3-butanedione and di-n-butylamine areadded to the solution at room temperature. The reaction mixture isheated to reflux (78° C.) and maintained at this temperature for onehour. Cooling the mixture to 0° C. produced 9.1 g (23%) of vacuum driedintermediate monomer as an off-white powder.

The quinolizinium resin monomer has the following properties: mp 204° C.(decomposition); ir (nujol) 1615(d) cm⁻¹ ; nmr (D₂ O) δ 2.55 (3H,s);2.62 (3H,s), 5.77 and 6.17 (2H,m), 6.9 (1H,m), 8.1 (3H,m) and 8.75(2H,s).

EXAMPLE IV Preparation of Poly-2,3-dimethyl-7-vinylquinolizinium Ionfollowing Reaction II

Charges

1.6 g (0.006 mole) 2,3-Dimethyl-7-vinylquinolizinium Bromideintermediate monomer

0.08 g Azo-bis-isobutyronitrile

10 ml Ethanol

0.25 g Divinylbenzene (80%)

The reactants are placed in a 50 ml flask containing a nitrogeninlet-outlet system. The system is flushed with nitrogen and a constantnitrogen sweep is maintained throughout the reaction period. The mixtureis heated to 65° C. and held at this temperature for 18 hours. The darkamber polymer is washed with acetone and vacuum dried (50° C.) to give1.13 g of quinolizinium polymer (Br form). The polymer is ground to afine particle size and converted to the chloride form using 7%hydrochloric acid.

    ______________________________________                                        Solids (%)              12.19                                                 Anion Exchange Capacity (meq/g dry)                                                                   5.49                                                  True Strong Base (meq/g dry)                                                                          3.83                                                  ______________________________________                                    

EXAMPLE V Silica Removal

The quinolizinium ion resin efficiently removes silica in a columnoperation using an 8 lb. regeneration level and 2 gpm/ft³ flow rate. Asshown in the following table, Resin A with a strong base capacitymeasuring 47% of the SBC of IRA-400, removes silica with a columncapacity equal to 58% of IRA-400.

    ______________________________________                                               True Strong                                                                              Regeneration Silica Capacity                                       Base       Level (a)    (b,c)                                          Resin  (meq/g)    (lb NaOH/ft.sup.3)                                                                         (Kilograins/ft.sup.3)                          ______________________________________                                        IRA-400                                                                              4.0        8            16.8                                           IRA-400                                                                              4.0        20           22.0                                           Resin A                                                                              1.7        8             9.7                                           Resin A                                                                              1.7        20            9.9                                           ______________________________________                                         (a) Room temperature regeneration                                             (b) Determined at 1 ppm silica leakage.                                       (c) Influent contained 200 ppm HCl and 19 ppm SiO.sub.2                  

I claim:
 1. A vinyl quinolizinium anion exchange resin polymer producedby quaternizing substituted vinyl pyridine polymer or polymerizing aprefunctionalized vinyl quinolizinium monomer in which the vinyl group,--CH═CH₂, is bonded directly to a quinolizinium ring carbon atom, ineither case optionally including a crosslinking comonomer in thepolymerization.
 2. The anion exchange resin polymer of claim 1 in whichthe polymer has the following formula: ##STR3## wherein R₁, R₂, and R₃are independently selected from hydrogen, lower alkyl phenyl,substituted lower alkyl, alkoxy and cyano and X is a negativecounterion.
 3. The anion exchange resin of claim 2 wherein R₁ = H, R₂and R₃ = CH₃ and X is Br⁻.
 4. The anion exchange resin of claim 2wherein R₁, R₂, and R₃ are hydrogen.
 5. The anion exchange resin ofclaim 2 wherein R₁ = CH₃ and R₂ and R₃ = hydrogen.
 6. The anion exchangeresin of claim 2 wherein R₁ = CN and R₂ and R₃ are hydrogen.
 7. A methodof preparing a quinolizinium resin which comprises quaternizing with acompound of the formula: ##STR4## A substituted vinyl pyridine polymerand subjecting the resulting product to a condensation reaction with acompound of the formula: ##STR5## to obtain the resin havingquinolizinium functionality, where R₁ is any activating group and may bealkoxy, carbonyl or cyano; where R₂ and R₃ are hydrogen, lower alkyl,phenyl, substituted lower alkyl, alkoxy or cyano groups; where R₁, R₂and R₃ may be the same or different; and where x is hydroxyl or halogen.8. An adsorption process which comprises using the quinoliziniumpolymeric composition of claim 1 as an adsorbent for silica from aliquid mixture comprising the same.